The invention relates to a projection arrangement for projecting an image onto a projection surface.
Such a projection arrangement is, for example, a projector for projecting a motion picture, which comprises a light source, a mechanical film stage and a projection lens. The light source emits a light ray bundle which illuminates positive images on a film guided transversely to the light propagation direction of the light ray bundle. The illuminated positive images are projected onto a screen by the projection lens. During operation, the film is unwound from a film reel or a film disk on one side of the film stage, guided across said film stage, and wound up on the other side of the film stage on another film reel or another film disk. The film is guided discontinuously across the film stage such that the film is moved past a picture gate on the film stage and stopped, 24 times per second, each individual image being illuminated twice. At the same time, the control signals for the theater sound system are also sampled. Such projector only allows conventional movies to be projected. A projection of movies, which are present only as digital and/or analog data and for the projection of which the images to be projected have to be generated first on the basis of said data, is not possible.
However, such movies have a number of advantages over conventional movies. Thus, it is possible to distribute such movies faster and more easily than conventional movies, because either a data carrier (e.g. a DVD), on which the data are recorded, may be shipped or the data may be transmitted directly via data lines, and it is no longer necessary to ship heavy film reels. Further, the quality of image and sound remains unchanged even after frequent screenings, while the quality of conventional movies may deteriorate with each screening. For the projection of such movies, which are present only as data, there are projection devices which comprise light modulators for imaging, said light modulators allowing to generate the image according to said image data. As light modulators, for example, LCD modules or tilting mirror matrices (DMD chips) are used. If the projector for projecting conventional movies is replaced by such projection arrangement, this will result in a high cost of acquisition, since an entire projection arrangement needs to be acquired. Further, such projection arrangement will no longer allow conventional movies to be screened.
EP 0,961,502 A2 describes a movie projector for projecting digital movies. This movie projector consists of the light source of a conventional movie projector for projecting conventional movies and of a digital front module, which is fixed to the housing of the light source instead of the film stage. This allows to convert a conventional movie projector to a digital projector and to save costs, because the light source of the conventional projector can be used for said digital projector. However, said digital projector still has the disadvantage that it is no longer possible to project a conventional movie. Also, said conversion is labor-extensive, because the film stage needs to be dismounted completely.
Now, the invention is intended to remedy this and to improve the aforementioned projection arrangement such that the projection arrangement is suitable for the projection of both a positive image recorded on a carrier medium and of an image to be generated on the basis of predetermined image data. Moreover, a supplementary module for use with such projection arrangement is to be proposed.
According to the invention, this problem is solved by a projection arrangement for projecting an image onto a projection surface, said arrangement comprising a light source, a control unit, a light modulator, which is controllable by said control unit in order to generate an image on the basis of digital and/or analog image data, an optical device, arranged following said light modulator, for projecting said image onto the projection surface, a film stage for holding a positive image recorded on a carrier medium, projection optics, arranged following the film stage during projection, and a control device, allowing either to direct light from the light source to the light modulator or to illuminate a positive image, which is held by the film stage, with said light.
In an advantageous embodiment of the projection arrangement according to the invention, the control device comprises an optical deflecting element (e.g. a mirror), which may direct the light from the light source to the light modulator. Said optical deflecting element may be moved back and forth between a first position, in which it is arranged in the optical path of the light emitted by the light source, between the light source and the projection optics, and in which it deflects said light, and a second position, in which it is not arranged in said optical path and, consequently, does not deflect the light to the light modulator. Preferably, said optical deflecting element is disposed between the light source and the film stage. Thus, there is no need to dismount the film stage and, at the same time, a compact configuration of the projection arrangement according to the invention may be realized as well.
Preferably, the projection arrangement according to the invention may be further embodied such that the light modulator is movable into an optical path extending from the light source via the film stage to the projection surface. Thus, the optical path of the projection arrangement remains unchanged, so that a simple construction of the projection arrangement may be realized.
The projection arrangement according to the invention may be further embodied such that the control device comprises an optical path switch arranged in the optical path between the light source and the projection optics, or arranged following the film stage. Preferably, said optical path switch may be an electronically switchable element, so that no mechanical movement of components is required for switching the optical path.
The light modulator, the optical device and the control device are preferably provided as an attachable module. On the one hand, this allows the use, as the light source for the light modulator, of the light source of a conventional projector for projecting positive images. On the other hand, the mechanical film stage and the associated projection optics of the conventional projector can remain as they are, so that conventional movies may continue to be projected. Further, the conversion of an already existing, conventional projector to the projection arrangement according to the invention is easily possible, since, due to the control device, the mechanical film stage of the conventional projector need not be dismounted.
Preferably, the projection arrangement according to the invention may be further embodied such that the control device comprises a device by which the light source is movable from a first position, in which the light is incident on the light modulator, to a second position, in which the light is incident on the film stage. Alternatively, the control device may comprise a device by which the light modulator is movable together with the film stage from a first position, in which the light is incident on the light modulator, to a second position, in which the light is incident on the film stage. Said device of the control device ensures that the images generated on the basis of the predetermined image data, or conventional positive images, may be projected.
Particularly advantageously, the projection arrangement according to the invention may be further embodied such that a splitting device is provided, which splits the light from the light source into different color components, and that the light modulator comprises several light-modulating units, each of which modulates one of said color components. This configuration allows to obtain light outputs which meet the brightness requirements of movie theaters.
In a further advantageous embodiment of the projection arrangement according to the invention, combining optics are provided which combine the light emitted by light-modulating units to form one single light bundle and guide it to the optical device. This advantageously allows the modulated light of different colors to be imaged onto the screen by means of an optical device.
Preferably, the projection arrangement according to the invention is further embodied such that the light modulator comprises an LCD modulexe2x80x94which may be in the form of a transmission or reflection modulexe2x80x94a GLV module, or a tilting mirror matrix. Thus, a high-quality image may be generated.
In a further advantageous embodiment, the projection optics and the optical device of the projection arrangement according to the invention are comprised in one single projection device. Thus, it is possible to provide a projection arrangement requiring only one projection device, which allows to save costs.
The projection arrangement according to the invention may advantageously be further embodied such that a memory for storing data is provided. Said memory may be a digital memory, e.g. a computer hard disk, or may also be an analog memory, such as a conventional video tape. By providing such memory, the entire movie may be stored in the projection arrangement, so that there is no need for high transmission capacities of a connection with an external movie memory.
In another advantageous embodiment of the invention, the projection arrangement according to the invention comprises an interface for receiving data. Said interface may be, for example, a DVD drive. It may also be an interface for a computer network, such as the internet. This allows new movies to be transmitted to the projection arrangement as fast as possible and to be projected after or even during transmission.
In a further advantageous embodiment of the invention, a display device and an image recording device are provided, said image recording device being able to record the image projected onto the projection surface and to represent it on the display device. When the image recording device records the film projected onto the projection surface and reproduces it on the display device, it is possible to control the performance from outside the auditorium. Thus, for example, failure of the projection lamp or of the auditorium lighting may be diagnosed at once.
Further, the projection arrangement according to the invention may comprise several projection units, each comprising a light source; a film stage, arranged following said light source, for holding a positive image recorded on a carrier medium; projection optics, arranged following the film stage when projecting the positive image; and a first coupling member; said projection arrangement further comprising a control unit; a supplementary module comprising a light modulator which is controllable by the control unit in order to generate an image on the basis of predetermined image data; an optical device, arranged following the light modulator, for projecting said image onto the projection surface; and a second coupling member, wherein the supplementary module may be coupled to the projection units via said coupling members, and wherein said supplementary module further comprises a control device, allowing either to direct light from the light source of that projection unit to which the supplementary module is coupled, to the light modulator or to illuminate a positive image, which is held by the film stage of said projection unit, with said light. This projection arrangement advantageously allows to provide only one supplementary module for several projection units and to couple said supplementary module to the corresponding projection unit, as required.
The supplementary module according to the invention for use in a projection arrangement as described above comprises a control unit, a light modulator, which is controllable by said control device in order to generate an image on the basis of predetermined image data, an optical device, arranged following the light modulator, for projecting said image onto a projection surface, and a control unit, which device, when the supplementary module is in a condition coupled to a projector comprising a light source and a film stage, arranged following said light source, for holding a positive image recorded on a carrier medium, allows either to direct light from the light source to the light modulator or to illuminate a positive image, which is held by the film stage, with said light. This supplementary module allows easy and fast retrofit of a conventional projector, so that it may project either a positive image recorded on a carrier medium or an image generated on the basis of predetermined image data, as required.